When a fire brigade arrives, why does it pour water on the burning material?

To bring the temperature of combustible material below its ignition temperature.

The correct answer is option 4. To bring the temperature of combustible material below its ignition temperature.

Fire brigades pour water on the burning material because water cools the combustible material so that its temperature is brought below its ignition temperature.

This prevents the fire from spreading.

Water vapours also surround the combustible material, helping in cutting off the supply of air.

So, the fire is extinguished.